What is Blue Light and What are the Risks?

If you spend your evenings watching TV or catching up on the day’s happening on your electronic device before bed, you may be exposing yourself to too much blue light putting you at risk for sleep issues and much more.

What is Blue Light?

Light is comprised of electromagnetic particles that travel in waves.  Although the rays of the sun look colorless, they are in fact made up of shades of red, orange, yellow, green, blue and violet. Our eyes are sensitive to a narrow band of frequencies referred to as the visual light spectrum which consists of wavelengths of varying lengths.

At one end of the visual light spectrum is red which has long wavelengths and inherently less energy. Found at the other end, blue has a short wavelength with a higher amount of energy.  This high energy, short wavelength affects levels of melatonin more than any other wavelength does.

Where is Blue Light Found?

The majority of our exposure to blue light comes naturally from the sun.  However, digital screens such as smartphone and tablets, TVs, computers, and laptops as well as fluorescent and LED lighting also generate blue light.  This artificial light has a higher proportion of blue light than natural light. With the explosion in the use of electronic screens and lighting from sources other than traditional incandescent sources, our exposure to blue wavelengths after sundown has soared.

What Effect Does Blue Light Have on Us?

Blue wavelengths are beneficial during daylight hours because they boost our attention, reaction times and mood. Think about how on sunny days people are more upbeat.  But excessive exposure to blue light at night can be disruptive. The blue light emitted from digital screens and lighting can delay the release of sleep-inducing melatonin; it tricks our bodies into thinking it is daytime when it’s not and makes it harder for us to settle down to sleep.  Before artificial lighting, the human body’s internal clock cycle, known as circadian rhythm, synced with the natural day and night cycles. We woke up when the sun rose and went to sleep when the sun went down.

Now with all of us constantly attached to our electronic devices watching TV, reading or staring at our news and social feeds on our devices before bedtime, our circadian rhythms are being completely disrupted.

Our eyes have receptors that contain a photopigment called melanopsin that is sensitive to blue light. These cells give information to our body that regulates our sense of day and night.  So when we are exposed to blue light at night our brains are getting messages to reduce melatonin secretion, which is a timing signal telling us to be awake when we should actually be getting ready to sleep.

Studies have shown that short-wavelength / blue light has a greater effect on phase shifting the circadian clock and on melatonin suppression. A  2014 study examined the impact of reading on a light-emitting device compared with reading a printed book. Participants who read on light-emitting devices took longer to fall asleep, had less REM sleep (the phase when we dream) and had higher alertness before bedtime than those people who read printed books. Researchers found that after an eight-hour sleep episode, those who read on the light-emitting device were sleepier and took longer to wake up.

Our sleep is not the only thing that is adversely affected by blue light. Studies have also shown that people exposed to more bright light at night are hungrier and produce less insulin as melatonin helps ward off hunger.  When we have less insulin, we don’t burn as many calories. Instead we store them in our blood or we store them as fat which increases our risk for diabetes.

Melatonin is also an anti-cancer agent, so with disrupted melatonin cycles we have an increased risk of cancer. A study conducted by researchers at the Tulane University Center for Circadian Biology found that female night shift workers were 50% to 70% more likely to develop breast cancer.

When our internal clocks are off not only do we experience poor sleep, reduced concentration, and cranky moods but studies show that over time our risk of depression, diabetes, and cancer is increased. “The more research we do, the more evidence we have that excess artificial light at night can have a profound, deleterious effect on many aspects of human health,” says Charles Czeisler, Professor of Sleep Medicine, Director of the Division of Sleep Medicine at Harvard Medical School and Chief of the Division of Sleep Medicine in the Department of Medicine at Brigham and Women's Hospital. “It is a growing public health concern.”

Teens, Devices and Sleep Issues

Anyone who has tried to get a teenager up in the morning is keenly aware of the natural shift in circadian rhythms that teens experience.  Couple that with the significant time teens spend on their devices and the impact of blue light is concerning. A study on teens from the Lighting Research Center (LRC) at Rensselaer Polytechnic Institute showed that 1-hour and 2-hour exposure to light from self-luminous devices significantly suppressed melatonin by approximately 23% and 38% respectively. Compared to previous studies, the results suggest that adolescents may be more sensitive to light than other populations.

Consequently, blue light can help teens who struggle early in the morning. Another study from Rensselaer Polytechnic Institute LRC shows that exposure to morning short-wavelength "blue" light has the potential to help sleep-deprived adolescents prepare for the challenges of the day and deal with stress, more so than dim light.

What can you do about it?

Scientists say that exposure to bright, blue-rich white light during the day, and to softer, amber hues at night, can help restore the human body’s natural circadian rhythm. Harvard Medical School offers the following tips for protecting yourself from blue light at night:

• Use dim red lights for night lights. Red light has the least power to shift circadian rhythm and suppress melatonin.
• Avoid looking at bright screens beginning two to three hours before bed.
• If you work a night shift or use a lot of electronic devices at night, consider wearing blue-blocking glasses or installing an app that filters the blue/green wavelength at night.
• Expose yourself to lots of bright light during the day, which will boost your ability to sleep at night, as well as your mood and alertness during daylight.

Lighting systems that support human-centric lighting (HCL) offer tunable capabilities that allow lights to be set to brighter hues in the morning and then to softer amber shades in the evening as the sun goes down help restore our circadian rhythms.